1. Field of the Invention
The present invention relates to a yellow ink composition, and more particularly to a yellow ink composition suitable for ink jet recording.
2. Background Art
Various properties are required of images produced by ink compositions, and one of them is lightfastness. When color images are produced using ink compositions, it is common practice to use at least a magenta ink, a yellow ink, and a cyan ink. Each of the inks should meet property requirements that are generally required of ink compositions, for example, stability of composition or properties upon storage. In addition, the inks should produce sharp images on recording media, and the images produced on the recording media should be stable upon storage for a long period of time.
In the production of color images using a plurality of ink compositions, presence of even one color having poor lightfastness causes a change in hue of the printed images. This results in remarkably deteriorated quality of color images. Therefore, more strictly controlled lightfastness is required of color ink compositions.
In recent years, ink jet recording printers have begun to widely spread. Ink jet recording is a printing method wherein droplets of an ink composition are ejected and deposited onto a recording medium, such as paper, to conduct printing. This method has a feature that images having high resolution and quality can be printed at a high speed by means of relatively inexpensive devices. In particular, color ink jet recording devices can provide images having improved quality, are used as output devices for photographs, and have become used as digital printing machines, plotters, CAD output devices and the like. Images printed by ink jet recording printers, which have become widely used, are considered usable in various forms. In particular, photograph-like prints produced by the ink jet recording printers are considered to be put as displays in places exposed to lights from fluorescent lamps or direct sunlight in outdoors and the like for a long period of time. Therefore, lightfastness is a very important property requirement for images produced by ink jet recording.
C.I. Pigment Yellow 74 has hitherto been widely used as a colorant for yellow ink compositons. This pigment is superior especially in yellow color development. However, there is still room for improvement in lightfastness.
Japanese Patent-Laid Open No. 25440/1998 proposes an ink composition, for ink jet recording, containing C.I. Pigment Yellow 154. This publication, however, discloses neither the addition of other pigments including C. I. Pigment Yellow 154 in combination with C.I. Pigment Yellow 74 to the ink composition nor advantages attained thereby.